1. Field of the Invention
The present invention relates generally to electromagnetic energy curing systems and more particularly to an ultraviolet curing device adapted to determine operating status of a shutter in light cure wand systems.
2. Brief Description of Related Technology
The use of ultraviolet radiation for curing inks, coatings, adhesives and other types of compounds is well known. In recognition of the many advantages attendant to the use of ultraviolet curing, various known ultraviolet curing systems have been developed for use in adhesive bonding applications such as medical device assembly, electronic assembly, conformal coating rework, wire tacking, potting and sealing, fiberoptic splicing, glass and crystal bonding, and stereo lithography.
One known ultraviolet curing system which is representative of many such systems currently available in the marketplace is manufactured by Henkel Corporation and sold under the trade name “Loctite Light Cure Wand Systems”. This particular device generally comprises a housing which is adapted to be placed upon a support surface such as a counter top and includes miniature arc lamp disposed therewithin for providing a source of ultraviolet light. Also disposed within the housing is a power supply which is electrically interfaced to the lamp and to a fan which is attached to the housing and adapted to circulate air therethrough to cool the lamp during its operation. Releasably attached to the housing is one end of an elongate, flexible wand which is liquid filled and adapted to transmit the ultraviolet light from the light source to an ultraviolet curable compound proximate the distal end of the wand. In the wand, liquid is used as the ultraviolet transmission medium since other transmission mediums such as optical fibers are less efficient.
Disposed between the arc lamp and the end of the wand attached to the housing is a mechanical shutter mechanism which is selectively actuatable between open and closed positions by a solenoid which is mechanically coupled thereto and electrically interfaced to the power supply. The actuation of the shutter mechanism to the open position facilities the transmission of ultraviolet light from the lamp into the wand, while the actuation of the shutter mechanism to the closed position blocks such transmission.
Though this system is generally sufficient for exposing an ultraviolet curable composition to ultraviolet light for purposes of curing the composition, these systems require a means to determine and respond to malfunctioning of the shutter for safety purposes. In other words, the system needs to determine if the shutter is an unintended open or closed state. An unintended open state of the shutter can result in very high intensity UV light up to 25 W/cm^2 being irradiated. Alternatively, an unintended closed state can result in an uncured or insufficiently cured product. Additionally, it is required that the system respond to such unintended states of the shutter and further take additional measures for its protection.